This invention relates to turbo-machinery vibration protection systems and, more particularly, to a machine protection system architecture using vector averaging and vector-based anomaly detection with estimated proximity probe vibration baselines.
An important prerequisite of any machine protection system (MPS) or a condition monitoring system (CMS) is fault detection. Equipment condition (static or dynamic) is determined through a set of sensor measurements that provides thermal, force, motion, chemical, optical and other related information. Equipment malfunctions or excursions from normal operational domains are then determined by identifying which sensor (or set of sensors) measurements have exceeded their set limits. Thus, detection of anomalies in sensor measurements is important for fault detection.
Typical turbo-machinery vibration protection systems utilizing proximity probe data use only amplitude information. A system that uses both amplitude and phase is not available. Similarly, most machinery protection systems algorithms only perform overall amplitude limit checking. Algorithms based on baseline comparisons are similarly not available.
There are three types of vibration measurements, i.e., displacement, velocity and acceleration. Even though velocity and acceleration are vector quantities, only amplitude values of these quantities are typically used in measuring and estimating alarm limits. Vibration displacement estimation, however, should include measurement of both amplitude and phase.
In an exemplary embodiment of the invention, a machine protection system for rotating equipment includes a control system and a vector sensor unit communicating with the control system that senses vibration amplitude and phase. The control system controls operation of the rotating equipment based on the vibration amplitude and phase. The vector sensor unit preferably includes a proximity probe and an angle position sensor. The control system may include a memory storing baseline vibration amplitude and phase data in a unit circle, and a comparison unit that compares the sensed vibration amplitude and phase with the baseline vibration amplitude and phase data. In this context, the memory stores separate baseline vibration amplitude and phase data according to an operating mode of the rotating equipment. A comparison unit outputs a signal based on the comparison, and a central processing unit of the control system controls the operation of the rotating equipment based on the signal from the comparison unit.
In another exemplary embodiment of the invention, a method of operating a machine protection system for rotating equipment includes the steps of sensing vibration amplitude and phase of the rotating equipment, and controlling operation of the rotating equipment based on the vibration amplitude and phase. The stored baseline amplitude and phase data may be determined using a rolling average and variance. The method may include tracking the baseline amplitude and phase data using short term average and long term average baselines. The short term averages are preferably determined on a minute-by-minute basis using data accumulated over an hour, and the long term averages are preferably determined in quarter-hour intervals using data accumulated over 100 hours. Spikes that exceed two times a standard deviation are discounted. In one arrangement, the baseline amplitude and phase data is entered manually. In this context, after collecting a predefined number of data values, the manually entered baseline amplitude and phase data is updated based on the predefined number of data values. If the sensed vibration amplitude and phase exceed the baseline vibration amplitude and phase data by a preset deviation, an alarm is triggered. The triggering step may further include shutting down the rotating equipment.